Grinding wheel



Patented Feb. 10, 1942 GRINDING WHEEL Samuel S. Klstler, West Boylston, Masa, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts No Drawing. Application August 2, 1941, Serial No. 405,245

8 Claims.

The invention relates to grinding wheels and other abrasive bodies bonded with organic bond.

Oneobject of the invention is to provide an improved dry snagging wheel. Another object of the invention is to provide a grinding wheel or other abrasive body which, in various embodiments, may be substituted for abrasive bodies bonded with shellac, rubber, or phenol formaldehyde, and which will remove a greater amount of metal for a given wheel wear.

Another object of the invention is to provide a resin bond for the manufacture of grinding wheels and other abrasive bodies having a chemical reaction with the work piece to increase the abrading action. Another object of the invention is to provide an ingredient for addition to an aromatic amine-aldehyde polymer which causes additional curing thereof when heated.

Another object of the invention is to improve an aniline formaldehyde polymer. Another ob- J'ect of the invention is to improve an aniline formaldehyde bonded grinding wheel or other abrasive body.

-Another object of the invention is to get an acid to the surface of the work piece being ground without spreading it all over the work piece, thereby increasing the effectiveness of the grinding operation without etching the work piece or causing it to rust or otherwise detrimentally affecting it and without such disadvantages as ticize them with furfural, for example, then add hydes.

spraying acid upon the operator, upon the grind- 'ing machine, or corroding the coolant pipes or tity of a primary aromatic amine, a quantity of aldehyde, and a quantity of a chlorinated or brominated fatty oil acid or its ester. These halogenated fatty oil acids and their esters react with the polymer of the aromatic amine and al-.

, dehyde by alkylating it or by migration of the hydrogen halide to the polymer or in both these ways. According to the present invention I take aniline or other primary aromatic amine and formaldehyde or other aldehyde and condense them in the presence of a strong acid, and then i I modify the condensate with a halogenated fatty oil acid orits ester. Preferably I first produce a polymer from the reaction of one molecular proportion of aniline with between one and. three molecular proportions of formaldehyde in the presence of at least approximately one molecular the aniline formaldehyde polymer together with the halogenated fatty oil acid or its ester. From the mixture I mold an abrasive body, press and heat the whole to a temperature capable of causing further reaction and sufficient to fuse the aniline formaldehyde resin.

The invention contemplates the use of any primary aromatic amine. Aniline is the preferred example but I may also use metaphenylene diamine' or meta toluidine or diamino diphenyl methane. The preferred aldehyde used in my invention is formaldehyde and so 'far as I now know this gives better results than other alde-' Secondly, however, I may use furfural to prepare the aromatic amine resin. A distinction must be made between a furfural aromatic amine resin as such and an abrasive body the abrasive grains of which were plasticized with furfural and the bond of which is modified aromatic amine formaldehyde. I find that as a practical matter to facilitate the use of the dry granular mix method of making abrasive articles, it is quite desirable to plasticlze the abrasive grains with fm'fural. However, within the scope of the ingrains and oil or ester may be hot pressed, and

the use of a liquid plasticizer may be dispensed Hydrochloric acid Oxalic acid Phosphoric acid Picric acid Tri-chloro, acetic acid Sulphuric acid Di-chloro acetic acid Hydriodic acid. Maleic acid For plasticizin g the abrasive grains I may as aforesaid use furfural or any other suitable plastlcizer or none at all. when furfural is used the furyl group substitutes for the hydrogen atoms on benzene rings of the polymer and forms a connecting link between chains, thus adding strength to the resin.

Examples of the halogenated fatty oil'acids and esters are the chlorinated and brominated ethyl succinate, the-chlorinated and brominated linoleic acids, chlorinated and brominatedlinseed and China wood oils, and any chlorinated or brominated alkyl ester of such acids.

I It will be noted that I have mentioned the chlorinated and brominated products only. The

fluorine compounds are believed to be too stable to alkylate the resin satisfactorily. It is difilcult to prepare iodated compounds of these oils and esters. Accordingly the halogenated oils and esters that are useful in my invention are the chicin the presence of a strong acid, reacts with formaldehyde, HCHO, to produce a long chain polymer, which when an excess of formaldehyde of above the stoichiometric proportions is used, for example 20% excess of formaldehyde, has adjacent chains connected wtih methylene groups to form a tough, heat resistant, semithermoplastic resin. When any one of the oil acids or esters is added to the polymer formed from aniline and formaldehyde and-the mixture is heated to between 130 C. and 190 C., the oil acid or esteralkylates the aniline formaldehyde attaching itself to the secondary amine groups. When such a resin is used for the bond of a grinding wheel, I find that superior results in grinding can be achieved. The invention has particular utility when embodied in snagging wheels the purpose of which is to clean off the fins, risers, cores and the like from rough castings and to smooth billets and the like prior to rolling. Snagging involves the removal of much metal and usually in snagging operations the desideratum is to remove as much metal as quickly as possible with a minimum amount of wheel wear. It is my belief that some of the improved results in grinding with wheels made according to the present invention are due to the release of hydrogen chloride or hydrogen bromide at the grinding line from the bond caused by the generation of heat at this line, and the reaction I of the thus liberated acid halide with the metal ance with the present invention, I may proceed as follows:

Example I Eight hundred and fifty-eight cubic centimeters of aniline is dissolved in eightliters of water containing nine and three-tenths mols of hydrochloric acid. To this is added sevenhundred and fifty cubic centimeters of formalin solution containing four tenths gram of formaldehyde'per cubic centimeter. After standing for one hour a quantity of sodium hydroxide is added equivalent to the hydrochloric acid present. The precipitated resin is filtered, washed, dried, and ground to a fine powder. Into each ten pounds of this powdered resin I mix two and twotenths pounds of chlorinated oleic acid.

complished without the use of any liquid acid and, in fact, without any free acid excepting at the grinding line. At this point alone is the temperature high enough to liberate the acid from the molecule and cause its reaction with metal.

Furthermore, as an added advantage, these oil acids or esters harden the aniline-formaldehyde and raise its heat resistance. It is hig y desirable to provide strong bonds for snagging wheels. However, the invention may frequently be embodied in grinding wheels or other abrasive bodies other than snagging wheels, and for some uses a weaker bond may be desired, wherefore those oil acids or esters which may'not increase the hardness or thermal resistance of aniline formaldehyde or other aromatic amine-aldehyde the manufacture of grinding wheels in accordsecondary 9.1111118 groups.

Twenty-eight and one tenth pounds of a porous, relatively pure'grade of fused alumina abrasive, #20 grit size, is now wet with twentythree hundredths of a pound of furfural. Five and nine-tenths pounds of the above mixture of aniline formaldehyde resin and the chlorinated oleic acid are intimatelymixed with the fused alumina wet with furfural, spread in an eighteen inch mold with a five inch arbor, and hot pressed for one hour and a half at a temperature of 160 C. under a pressure of three tons per square inch. The wheel is then stripped from the mold.

As conducive to a clearer understanding of the present invention, I believe that the structural formula of the resin thus produced is as follows: i

, The above is the modified polymer formed when chlorinated oleic acid is used. It will be noted that the nitrogen atoms of the secondary amine groups are connected by the oleic acid residue. ,Hydrogen chloride is found attached to some of the secondary amine groups. Methylene links from excess formaldehyde are shown. Furyl 'groups are shown connecting some of the points on the benzene rings ortho to the These furyl groups were derived from the furfural used to plasticlze the abrasive grain. Naturally if enough furfural is used all of these ortho points will be connected, while if less than the saturating amount is used, only some of the ortho points will be connected. These furyl groups forming connecting links add strength to the resin. However, if furfural was used to condense the aniline formaldehyde, furyl rings would substitute for one of the hydrogen atoms on the connecting methylene groups.

This compound has the property of giving off hydrogen chloride when heated to a temperature of 500 C. At a temperature'far below that 1 point, it no longer gives up the hydrogen chloride.

Example II Thirty-seven pounds of #14 mesh fused alumina abrasive isplaced in a mixing pan and wet with five hundred and forty cubic centimeters of furfural. To this are added nine pounds of the resin and chlorinatedvoleic acid lite. Further mixing is caused and then the hundred and fifty tons for half and hour. This mixture thus produced (which is substantially wheel has characteristics similar-to the wheels of what is called a dry granular mix) is spread in the other examples. The structure of the chloa sixteen inch mold with a six inch arbor and rinated resin is as follows:

hot pressed for two hours at a temperature of 6 160 C. and under a pressure of five hundred tons. Such a wheel will give as good a finish on stainless steel as a rubber wheel but is much 1'! I n u: I

more durable. I

It may be noted at this point that cold press- 10 6 ing can be resorted to by reason of the "plastic- 0 H II I izing of the abrasive grains with furfural. I However, the results are not as satisfactory as 1 (m'mcoohwdnacl' when the hot pressing method is used. Furthermore, the addition of furfural definitely inc N creases the plasticity of the mix and provides 9. better product when hot pressed.

, Example Ill Nineteen hundred and eighty grams of diamine Example V diphenyl methane is dissolved in eight liters of water containing twenty mols of hydrochloric Nine hundred and thirty grams of aniline and acid. To this solution is added eight hundred .two liters of water containing eleven mols.of cubic centimeters of formalin solution containing hydrochloric acid are mixed with six hundred four-tenths gram formaldehyde per cubic cenand seventy cubic centimeters of furfural and timeter After standing for one hour a quantity heated to 80 C. overnight. The solid mix reof sodium hydroxide is added equivalent to the suiting is ground and suspended in water conhydrochloric acid used. The precipitated resin taining sodium hydroxide equivalent to the hyis filtered, washed, dried, and ground to a fine 3U drochloric acid used. A-fter neutralization is powder. complete, the powder is filtered, washed and Eight hundred and eighty-five grams-of dried. mesh fused alumina is mixed dry with; one Eight hundred and eighty-five grams of #60 hundred and sixty grams of the above powdered mesh fused alumina is first wet with thirty cubic resin and forty-nine grams of chlorinated China centimeters of furfural. Then one hundred and wood oil. .This mixture is spread in an eight sixty grams of the above powdered resin and inch mold and pressed at a temperature of 175 twenty grams of chlorinated linseed oil are add- C. under a pressure of one hundred and fifty ed and mixed to produce adry granular mix. tons for half an hour. This constitutes a grind- This mixture is spread in an eight inch mold and ing wheel the resin bond of which is hard, tough m pressed under a pressure of two hundred tons, and heat resistant. This bond likewise during then stripped from the mold and the green grinding liberates hydrogen chloride at the grindwheel is baked in an autoclave at a pressure of ing line. The structure of such resin bond may seven atmospheres at a temperature gradually be represented as follows:- rising to 175 C. and maintained at this tem- Example IV perature for three hours. The structure of the resin may be represented as follows: Ten hundred and eighty grams of metaphenylene diamine is dissolved in eight liters of water containing twenty mols of hydrochloric O H 7 Cl acid. To this solution is added six hundred 60 cubic centimeters of formalin solution contain- O ing four tenths gram of formaldehyde per cubic 1; I centimeter. After standing for one hour a quan- I tity of sodium hydroxide is added equivalent to -n (onmloooncsm c--- the hydrochloric acid used. The precipitated res- 5 0 I 0 in is filtered, washed, dried, and ground to a fine 3 powder. N

Eight hundred and eighty-five grams of #60 V.

mesh fused alumina is wet with twenty-two cubic H centimeters of furfural. To the thus wet abra- 7 sive grain are added one hundred and sixty grams 1 g of the above powdered resin and fifty grams of Example VI chlorinated China wood oil. This mixture .is

spread in an eight inch mold and pressed at a Ten hundred and seventy grams of meta tolutemperature of 175 C. under a pressure of one idine are dissolved in eight liters of water containing ten and two tenths mols of phosphoric acid. To this solution is added seven hundred and fifty cubic centimeters of formaldehyde so-.

lution containing four tenths of a gram of formaldehyde p'er cubic'centimeter. After standing for one hour, a quantity of sodium hydroxide is added equivalent to the phosphoric acid used. The precipitated resin is filtered, washed, dried and ground to a fine powder.

Eight hundred and eighty-five grams of 60 mesh fused alumina is first wet with thirty cubic centimeters of powdered resin and twenty grams of linoleic acid are added and mixedto produce a dry granular mix. This mixture is spread in an eight inch mold and pressed under a pressure of two hundred tons at a temperature of 150 C.

for one hour. It is then cooled and stripped from the mold, and is found to be a grinding wheel of superior quality.

Interpreting the foregoing diagrams, it mustbe understood that an approximat condition is what is illustrated. It would be impossible to illustrate all of the linkages. Furthermore, for anabsolutely accurate representation, a threedimensional structure would have to be represented.

For th acid used in condensing the resin, besides hydrochloric and phosphoric acids, any of the following acids may also be used:

Hydriodic acid Tri-chloro acetic acid Di-chloro acetic acid Maleic acid Oxalic acid Picric acid Sulphuric acid The requirement is that the acid should be at least as strong as phosphoric acid to give the It will thus be seen that there has been provided by this invention a composition of matter, an article of manufacture, and an art in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As variouspossible embodiments might be made of the me- "chanical features of theabove invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth is to be interpreted as illustrative and not in a limiting. sense.

I claim:

1. An abrasive body comprising abrasive grains bonded with the condensation product of one molecular proportion of primary aromatic amine and between one and three molecular proportions of aldehyde selected from the group consisting of formaldehyde and furfural condensed inthe presence of at least approximately one molecular proportion of acid at least as strong as phosand furfural, condensed in the presence of at least approximately one molecular proportion of acid at least as strong as phosphoric acid, and reacted by heating at resin curing temperatures with a halogenated organic substance selected from the group consisting of the chlorinated and brominated fatty oil acids and their esters.

3. An abrasive body comprising abrasive rains bonded with the condensation product of one molecular proportion of primary aromatic amine and between one and three molecular proportions of formaldehyde, condensed in the presence of at least approximately one molecular proportion of acid at least as strong as phosphoric acid and reacted by heating at resin curing temperatures with a halogenated organic substanceselected from the group consisting of the chlorinated and br ominated fatty oil acids and their esters.

4. An abrasive body comprising abrasive grains bonded with the condensation product of one molecular proportion of aniline and between one and three molecular proportions of aldehyde consisting at least in part of formaldehyde, condensed in the presence of at least approximately one molecular proportion of acid at least as strong as phosphoric acid, and reacted by heating at resin curing temperatures with a halogenated substance selected from the group consisting of the chlorinated and brominated fatty oil acids and their esters.

5. An abrasive body according to claim 1 in which furyl methylene groups connect some of the benzene rings of the resin polymer ortho to the amino groups thereof.

6. An abrasive body according to claim 2 in which furyl methylene groups connect some of the benzene rings of the resin polymer ortho to the amino groups thereof.

7. An abrasive body according to claim 3 in which furyl methylene groups connect some of the benzene rings of the resin polymer ortho to the amino groups thereof.

8. Arr abrasive body accordinglto claim 4 in which furyl methylene groups connect some of the benzene rings of the resin polymer ortlio to the amino groups thereof.

SAMUEL S. KISTLER. 

